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Editors Note: The original patch was modified to use SDL_Delay() instead of
nanosleep because nanosleep may not be portable to all systems
using SDL with the ALSA backend. This may be a moot point with
the switch to blocking writes anyway...
Date: Sat, 27 Dec 2003 21:47:36 +0100
From: Michel Daenzer
To: Debian Bug Tracking System
Subject: [SDL] Bug#225252: [PATCH] ALSA fixes
Package: libsdl1.2debian-all
Version: 1.2.6-2
Severity: normal
Tags: patch
For SDL 1.2.6, the ALSA backend was changed to call snd_pcm_open() with
SND_PCM_NONBLOCK. That's a good idea per se, however, it causes high CPU
usage, interrupted sound and stuttering in some games here. Taking a nanosleep
whenever snd_pcm_writei() returns -EAGAIN fixes this, but I think it's more
efficient to use blocking mode for the actual sound playback. Feedback from the
SDL and ALSA lists appreciated.
The patch also fixes the default ALSA device to be used.
author | Sam Lantinga <slouken@libsdl.org> |
---|---|
date | Sun, 04 Jan 2004 15:40:50 +0000 |
parents | e5bc29de3f0a |
children | 355632dca928 |
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<HTML ><HEAD ><TITLE >CDROM Examples</TITLE ><META NAME="GENERATOR" CONTENT="Modular DocBook HTML Stylesheet Version 1.64 "><LINK REL="HOME" TITLE="SDL Library Documentation" HREF="index.html"><LINK REL="UP" TITLE="Examples" HREF="guideexamples.html"><LINK REL="PREVIOUS" TITLE="Audio Examples" HREF="guideaudioexamples.html"><LINK REL="NEXT" TITLE="Time Examples" HREF="guidetimeexamples.html"></HEAD ><BODY CLASS="SECT1" BGCOLOR="#FFF8DC" TEXT="#000000" LINK="#0000ee" VLINK="#551a8b" ALINK="#ff0000" ><DIV CLASS="NAVHEADER" ><TABLE WIDTH="100%" BORDER="0" CELLPADDING="0" CELLSPACING="0" ><TR ><TH COLSPAN="3" ALIGN="center" >SDL Library Documentation</TH ></TR ><TR ><TD WIDTH="10%" ALIGN="left" VALIGN="bottom" ><A HREF="guideaudioexamples.html" >Prev</A ></TD ><TD WIDTH="80%" ALIGN="center" VALIGN="bottom" >Chapter 4. Examples</TD ><TD WIDTH="10%" ALIGN="right" VALIGN="bottom" ><A HREF="guidetimeexamples.html" >Next</A ></TD ></TR ></TABLE ><HR ALIGN="LEFT" WIDTH="100%"></DIV ><DIV CLASS="SECT1" ><H1 CLASS="SECT1" ><A NAME="GUIDECDROMEXAMPLES" >CDROM Examples</A ></H1 ><P ></P ><DIV CLASS="SECT2" ><H2 CLASS="SECT2" ><A NAME="AEN393" >Listing CD-ROM drives</A ></H2 ><P ><PRE CLASS="PROGRAMLISTING" > #include "SDL.h" /* Initialize SDL first */ if ( SDL_Init(SDL_INIT_CDROM) < 0 ) { fprintf(stderr, "Couldn't initialize SDL: %s\n",SDL_GetError()); exit(1); } atexit(SDL_Quit); /* Find out how many CD-ROM drives are connected to the system */ printf("Drives available: %d\n", SDL_CDNumDrives()); for ( i=0; i<SDL_CDNumDrives(); ++i ) { printf("Drive %d: \"%s\"\n", i, SDL_CDName(i)); }</PRE ></P ></DIV ><DIV CLASS="SECT2" ><H2 CLASS="SECT2" ><A NAME="AEN397" >Opening the default drive</A ></H2 ><P ><PRE CLASS="PROGRAMLISTING" > SDL_CD *cdrom; CDstatus status; char *status_str; cdrom = SDL_CDOpen(0); if ( cdrom == NULL ) { fprintf(stderr, "Couldn't open default CD-ROM drive: %s\n", SDL_GetError()); exit(2); } status = SDL_CDStatus(cdrom); switch (status) { case CD_TRAYEMPTY: status_str = "tray empty"; break; case CD_STOPPED: status_str = "stopped"; break; case CD_PLAYING: status_str = "playing"; break; case CD_PAUSED: status_str = "paused"; break; case CD_ERROR: status_str = "error state"; break; } printf("Drive status: %s\n", status_str); if ( status >= CD_PLAYING ) { int m, s, f; FRAMES_TO_MSF(cdrom->cur_frame, &m, &s, &f); printf("Currently playing track %d, %d:%2.2d\n", cdrom->track[cdrom->cur_track].id, m, s); }</PRE ></P ></DIV ><DIV CLASS="SECT2" ><H2 CLASS="SECT2" ><A NAME="AEN401" >Listing the tracks on a CD</A ></H2 ><P ><PRE CLASS="PROGRAMLISTING" > SDL_CD *cdrom; /* Assuming this has already been set.. */ int i; int m, s, f; SDL_CDStatus(cdrom); printf("Drive tracks: %d\n", cdrom->numtracks); for ( i=0; i<cdrom->numtracks; ++i ) { FRAMES_TO_MSF(cdrom->track[i].length, &m, &s, &f); if ( f > 0 ) ++s; printf("\tTrack (index %d) %d: %d:%2.2d\n", i, cdrom->track[i].id, m, s); }</PRE ></P ></DIV ><DIV CLASS="SECT2" ><H2 CLASS="SECT2" ><A NAME="AEN405" >Play an entire CD</A ></H2 ><P ><PRE CLASS="PROGRAMLISTING" > SDL_CD *cdrom; /* Assuming this has already been set.. */ // Play entire CD: if ( CD_INDRIVE(SDL_CDStatus(cdrom)) ) SDL_CDPlayTracks(cdrom, 0, 0, 0, 0); // Play last track: if ( CD_INDRIVE(SDL_CDStatus(cdrom)) ) { SDL_CDPlayTracks(cdrom, cdrom->numtracks-1, 0, 0, 0); } // Play first and second track and 10 seconds of third track: if ( CD_INDRIVE(SDL_CDStatus(cdrom)) ) SDL_CDPlayTracks(cdrom, 0, 0, 2, CD_FPS * 10);</PRE ></P ></DIV ></DIV ><DIV CLASS="NAVFOOTER" ><HR ALIGN="LEFT" WIDTH="100%"><TABLE WIDTH="100%" BORDER="0" CELLPADDING="0" CELLSPACING="0" ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" ><A HREF="guideaudioexamples.html" >Prev</A ></TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="index.html" >Home</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" ><A HREF="guidetimeexamples.html" >Next</A ></TD ></TR ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" >Audio Examples</TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="guideexamples.html" >Up</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" >Time Examples</TD ></TR ></TABLE ></DIV ></BODY ></HTML >